Pyrazole-3-carboxylic acids

ABSTRACT

Pyrazole-3-carboxylic acids, useful as complement inhibitors, are prepared by the alkaline hydrolysis of pyrazolo(1,5c)quinazolin-5(6H)-one-2-carboxylic acids or esters thereof.

United States Patent 11 1 Katner et al.

[451 Sept. 2, 1975 PYRAZOLE-3-CARBOXYLIC ACIDS Inventors: Allen S.Katner; Charles J. Paget;

William T. Jackson, all of Indianapolis, lnd.

Assignee: Eli Lilly and Company, Indianapolis,

lnd.

Filed: Apr. 12, 1974 Appl. No.: 460,647

U.S. Cl 260/310 R; 260/251 QB Int. Cl C07d 49/18 Field of Search 260/310R, 25l QB [56] References Cited UNITED STATES PATENTS 3,313,815 4/1967Wolfe et al. 260/310 R Primary Examiner-Donald B. Moyer Attorney, Agent,or FirmWilliam E. Maycock; Everet F. Smith [57 ABSTRACT 4 Claims, N0Drawings .1 PYRAZOLE-3-CARBOXYLIC ACIDS ,BACKCIRVOUNDOF'THE INVENTIONSUMMARY 10F THE NvENTio In accordance with thepresent invention, novelpyrazole-3-carboxylic acids'are provided having the following generalformula? wherein R is a monovalent group selected from the groupconsisting of hydrogen, C,C alkyl, phenyl, and monosubstituted phenyl inwhich the substituent is C -C alkyl, C -C alkoxy, fluoro, chloro, orbromo; R is a monovalent group selected from the group consisting ofmethyl, phenyl, benzyl, and monosubstit'uted phenyl and benzyl in whichthe substituent is methyl, trifluoromethyl, methoxy, fluoro, chloro,bromo, or methylsulfonyl; and R and R are monovalent groupsindependently selected from the group consisting of hy drogen, methyl,methoxy, fluoro, chloro, and bromo, with the limitation that R, and Rmust be different unless each of R and R is hydrogen.

The novel pyrazole-3-carboxylic acids of the present invention areuseful as complement inhibitors.

DETAILED DESCRIPTION OF THE INVENTION Examples of compounds comingwithin the foregoing general formula include, among others,

5-[Z-(Methylamino)phenyl]pyrazole-3-carboxylic acid5-(3-Anilinophenyl)pyrazole-3-carboxylic acid 5-[2-(3-Trifluoromethylanilino)phenyl]pyrazole-3- carboxyli acid I i4-Ethyl-5-[2-(2-fluoroanilino)phenyl]pyrazole-3-5-[2-(Benzylamino)-3-bromophenyl]pyrazole-3'- carboxylic acid 5'-[2-(4-Chlorobenzylamino )phenyl ]pyrazole-3- carboxylic acid I4-Methyl-5-[2-(4- V I chlorober'izylainino)phenyl]pyraiole-3-carboxylicacid 4-Ethyl'-5 [2-( 1- achlorobenzylamin'o)phenyl]pyrazole-3-carboxylic acid 4-Propyl-5-[2-(4- ichlorobnzylamino)phenyl]pyrazole-3-carbo$ ylic acidchlorobenzylainino)phenyl]pyrazole-3-carboxylic acid 4-( 3-Methoxyphenyl)-5[ 2-( 4- chlorobenzylamino)pli'enyl]-pyrazole-3 carboxylic acid 14-(4-Fluorophenyl)-5-[2-(3-chlor0benzylamino) 4- methylphenyl]pyrazole3-carboxylic acid i l 5-[2-(3 Methylsulfonylbenzylamino)-5-rnethoxyphenyl]-pyrazole-3-carboxylic acid 5-[2-(4-Chlorobenzylamino)-3-methylphenyl]pyrazole-3-carboxylic acid 5-[2-(4-Chlorobenzylainino)-5-rriethylphenyl]pyrazole-3-carboxylic acid 5-[2 (4-Chlorobenzylamino)-5-chlorophenyl]pyrazole-3-carboxylic acid 5- [2-(4Chlorobenzylamino)-3-methyl 6- chlorophenyl] pyrazole-3-carboxylic' acid5-[2-(4-Chlorobenzylamino)-4-chloro5 methoxyphenyl]-pyrazole-3-carboxylic acid.

Examples of preferred pyrazole-3-carboxylic acids include, among others,

5-(2-Anilinophenyl)pyrazole-3-carboxylic acid 5-[ 2-(3-Trifluoromethylanilino)phenyl ]pyrazole-3- carboxylic acid 5- [2(4-Chlorobenzylamino)phenyl]pyrazole-3- carboxylic acid.

The compounds of the present invention are readily obtained by thealkaline hydrolysis of a pyrazolo[ 1.5- c]-quinazolin-5(6H)-one havingthe general formula,

reactioncan be represented by the following reaction scheme whichillustrates the preparation (ifs- 2 4- carboxylic acid 55chlorobenzylamin'o)-phenyl]pyrazolo-3-carboxylic 4-Me'thyl-5-[2-(2-fluoroanilino) 4 chloro=6-' acid from ethyl6-(4-chlorobenzyl)pyrazolo[1,5- methylphenyl]pyrazole-3 carboxylic acidclquinaiolin-SI6H)-one-2-carbo)tylate.

" cooc n coon I solid which forms is isolated byfiltration and purifiedby dissolving the material in .hot ethanolic N,Ndimethylformamide andpouring the hot solution into water. The solid which precipitates iscollected and, if desired.

further purified. 1

Examples of-. suitable pyrazolo[ l.--c]quinazolin- 5(6H)-ones include,among others a I Ethyl 6-phenylpyrazolo['l,5-c]quinazolin-5(,6H')-one-Z-carboxylate v Methyl 6-[ 3'=(trifluoromethyl)phenyl] pyrazolo[l,5- c]-quinazolin-5(6H)-one-2-carboxylate Methyl6-(4-chlorobenzyl;)pyra2olo[l,5- c]quinazolin-5(6H) one-2-carboxylate IEthyl l-ethylF6-methylpyrazolo[Il ,5-c ]quinazolin-5(6H)-one-2-carboxylate' v Ethyl l-(3-methoxyphenyl)-6-( 3-methylsulfonylbenzyl)-8-fluoropyrazolo[ 1,5- 1 Ic]quina7.olin-5(6H)-one-2-carboxylate Methyll=-prop.yl-6-(4-bromophenyl) 7-methyl-10-methoxypyrazololl,S-c]quinalolin-5(6H)-o ne-2- carboxylate. I I i I Thepyrazolo[l;5 c]quinazolin-5(6H) ones used as starting materials toprepare the compounds of the present invention are prepared byreactingian activated acetylene with a 3-diazoindol-2(3H)-one, as shownby thefollowing cq-uation:- I I Typically. the reaction is carried outby heating at reflux a benzene solution of approximately equimolaramounts of an activated acetylene and a 3-diazoindol- 2(3H)-.one. Thereaction mixture then is worked up according to known procedures. The.reaction in'general is carried-out in a solvent which is inert to bothof the reactants. Examples of suitable solvents include.

S qlveitb two reactants are =employed, although anexcess of activatedacetylene can be used. if desired. Reaction time can vary from about 15minutes to about 24' hours and thereac tion temperature usually will bein the range of from about 40C to about, C

ln carrying out the above-described reaction, the activated acetylenepreferably will not contain a carboxy group; i.e.,'R preferably is-nothydrogen. An unprote'cted carboxy group can react with thewdiazo moietyof the 3-diazoindol-2(3H)-one to give an ester.

I The'activatedacetylene preferably reacts with the 3-diazoindol-2(-iiH).-one in such a manner asto give a .duces a pyrazole-4-carboxylicacid which undergoes intramolecular ..-condensa tion to give a lH-pyrazolo[4,3-c]quinol-4(5H).-one of the formula,

The tendency for the formation of said reverse additioncompoundincreases as the bulk of R increases. There-'pyrazolo[4,3-c]quinol-4(5H)-one clearly dimishes the yield ofpyrazole-3-carboxylic acid and is undesirable. The activated acetylenesin general are commercially available or readily prepared by well-knownprocedures. Examples of suitable activated acetylenes include. methyl,propiolate. ethyl phenylpropiolate, methyl =3-chlorophenylpropiolate,methyl Z-butynoate,

"and the like.

. The 3-diaioindol-2(3H)-ones are prepared in accordance with knownprocedures. See, for example, J. M. Michowski, Tetrahedron Letters, 1773(1967) and M. P. Cava, et al., J. Am. ChemlSoa, 80, 2257 (1958).Briefly, the appropriate isatin-compound is treated withp-toluenesulfonylhydrazine. The resulting hydrazone then is treated withaluminum oxide to give the desired 3-diazoindol-2(3H)-one. Thepreparation of the required isatin compound is well known in the art.The required N-substituted isatin is obtained by either of two routes,depending upon the nature of the desired N-substituent. When the desiredisatin nitrogen substituent is alkyl or aralkyl, the N-substitutedisatin compound is prepared by N-alkylation of the parent compound withan alkyl or aralkyl halide in the presence of a strong base such as, forexample, sodium hydride. An N-aryl isatin, on the other hand, isprepared directly by cyclization with oxalyl chloride of anappropriatelysubstituted diarylamine. v v

Examples of suitable 3- 'diazoiridol-2(3H)-ones include, among others,

l-Methyl-3-diazoindol-2(3H)-one l-(3-Methoxyphenyl)-3-diazo-5-bromoindol- 2(3H)-one l-( 4-Chlorobenzyl)-3-diazo-5-methoxy-6- chloroindol2( 3H )-one.

Complement inhibition activity of the compounds of the present inventionis determined by the test procedure of W. T. Jackson, et al., reportedat the 1971 Annual Meeting of the Federation of American Societies ofExperimental Biology and abstracted in Federation Proceedings, Vol. 30,No. 2 (March-April), 1971.

The procedure measures inhibition of the functioning of the latecomponents in immune hemolysis. Inhibition of the early components mightunfavorably alter susceptibility to infection. To carry out the test,sheep erythrocytes (E) are reacted with rabbit nemolysin (A) to formsensitized cells (EA). The EA cells then are incubated withiodineoxidized, zymosan-treated human sure of complement inhibitionactivity, expressed as percent inhibition of lysis. Thus, in any givenseries of test compounds, increasing activity results in increasingpercent inhibition of lysis values. With each test compound, a controlis conducted to correct the percent inhibition of lysis value obtainedfor compoundinduced lysis. Such a control is carried out by adding tothe EACl, 4 2 cells buffer solution containing the test compound. Theextent of,hemoglobin release is measured colorimetrically as describedabove. Such hemoglobin release is compared with the extent of hemoglobin release obtained from 100 percent cell lysis which results uponadding water to the cells. As before, the difference between the twohemoglobin release val ues provides a measure of compound-induced lysis,expressed as percent compound-induced lysis. The extent ofcompound-induced lysis is important for two reasons. First, extensivecompound-induced lysis adversely affects the accuracy and reliability ofthe test results. Second, and more important, compoundinduced lysispartly or entirely counteracts any activity a compound might have ininhibiting immune hemoly SIS.

Representative pyrazole-3-carboxylic acids of the present invention weretested by means of the abovedescribed procedure. The results aresummarized in Table I.

Table I Percent Inhibition of Lysis COOH Table I 1 continued 00110.; i iV Percent A ,ugzml Inhibition 560E unknown 2 i 't S Concentration-oftest compound expressed as pg compound per inll total test volume. Manycompounds were not soluble at the usual test concentration "of #00ug/ml.

In suchcases, the suspension obtained.- was filtered 2..

and the supernatant liquid tested.

The

concentration of the compound was estiniated and is so indicated by an"E" adjacent to the estiriiated value. Dilutions of this originalsupernatent liquid to give less concentrated solutions for testingnecessarily resulted in solutions having an' estimated concentration of'test compound.

0. percent compoundinduced lysis.

1.25 percent compoundinduced lysis' I 0.82 percent compound-inducedlysis.

nephritis, serum sickness, and certain inflammatoryn diseases such asrheumatoid arthritis.

Utilization of a complement inhibitor in general involves administeringto a mammal parenterally, preferably intravenously or intraperitoneally,an effective amount of such a compound, typically at a dosage level 60sufficient to provide a concentration of the compound in the blood offrom about 1 to about 400 ,ug/ml. Such a concentration on the averagecan be attained by the administration ofa dose of from about 0.05 to about 32 mg/kg. The necessaryconcentration in the blood of 55 complementinhibitor can be achieved by administering a single dose or up to aboutsix smaller doses per day, depending upon the tolerance of the patientto the compound, persistence of the compound in the blood stream, andother factors. Following procedures well known to those skilled in theart, the complement inhibitor normally is formulated into apharmaceutical composition comprising the activeingredient inassociation with at least one pharmaceutically-acceptable carriertherefor. Such a composition generally is prepared by incorporating thecomplement inhibitor in a liquid solution or suspension, except that asuspension is not employed for intrayenous administration. In such acomposition, the complementinhibitor ordinarily will be present in anamountof at least about 0.0001 and not more than about 50 percent byweight, based on the total weight of the composition.

Suitable pharmaceutical carriers are described in E. W. Martin, et al.,Remingtons Pharmaceutical Scicnces," 14th Ed, Mack Publishing Company,Easton, Pa., 1965.

complement inhibitor normally formulated into a pharmaceuticalcomposition comprising the active ingredient' in association. with .atleast one pharmaceutically-acceptable carrier therefor. For enteraladministration, the complement inhibitor normally is administered at alevel of from'about l to about 200 mg/kg of mammal body weight.Advantageously. the complement inhibitor is formulated in a dosage unitform containing from about 5 to about 500 mg, preferably from about IDto about l50 mg, of active ingredient. Examples of suitable dosage unitforms are. tablets, hard or soft gelatin capsules, micro-capsules, andsuppositories, as well as drug-dispensing systems comprising the activeingredient contained in a flexiblej'irnperforate polymeric materialthroughwhich the drug is released slowly by diffusion. 'Mbre generally,the term dosage unit form as used herein means a physically- I x I 12EXAMPLES 243 Following the procedure for Example 1, thefollowingciompounds were prepared from the indicated starting materials.The elemental analysis of each compound isgiven.

out intending to limit it in any manner, by the following examples whichillustrate the preparation of certain pyrazole-3-carboxylic acids of thepresent invention. In

the examples. all temperatures are in degrees centigrade, unlessotherwise specified.

EXAMPLE l a Preparation of 5-[ 2-( 4-chlorobenzylamino)phenyl]pyrazole-3- carboxylic acid.

A mixture or g of ethyl 6-(4- chlorobenzyl)pyrazolo-[ l ,S-c]quinazolin-5(6H)-one- 2-carboxylate, 500 ml of 20 percent aqueous potassium ia-steam bath'for 24'hou'rsi The' solution was distilled until 'theremaining volume was about 50ml. The resipe'i'siste'd; Themixture wascooled at about "5. The solid which resulted was' isola'tedbyfiltration. The solid, 1 1.3 mp l22 l- -3 l was recrystallized twice togive 5.2 *g of '5- 244 chlorobenzylamino )phenyl]pyrazole 3=carboxylicacid. mp l 35l 39. Th eassig ned structure was consistent withultraviolet and nuclear magnetic. resohance analyses. The followingelemental analysis was ob tained:

'due was cooled and diluted with wateruntil turbidity calcu latedfor C,H,;,N .O

n.1onohydrate.

5. Z M e thyI-aminOphenyl )pyrazole '3-carboxylic acid, mp 233-235(dec.). From ethyl methylpyrazolo[ l,5-c]-quinazolin-5( 6H )-one-2-carboxylate.

Calculated for C H N O z C, 60.32; H. 5.i0; N. 19.34

Found;

5-(2-Anilinophenyl)pyrazole-3-carboxylic acid, mp 209-2ll. From methyl6-phenylpyrazolo[l,5-

-.c]quinazolin-5(6H)-one-2-carboxylate.-,- I

c. 683i; H. 4.69; N. 15.05 Found:

,- c, 68.57; H. 4.91; N. l4.79

5-[ 2-( 3 -T riflu oromethylanilino )phenyl]pyra zole-3- carboxylic'acid, mp'llO -ll2. From methyl 6-[3- (trifluoromethyl)phenyl]pyrazolol l,5-c]quinazolinc. 59.05; H. 3.73; N. 12.33

hy [2-.,( I chlorobenzylamino)phenyl]pyrazole 3-carboxylic acid From\ethyl ,..l-methyl-6-(4- chlorobenzyl )pyrazolo[ l,5-c]quinazolin-5(6l-l)-one-2- carboxylate. 1 3

Calculated fo'r C M CIN O C. 60.09; H. 5.04; N. 11.68

Found: I

v C. 6|.76; H. 4.6l; N. 11.98

.4- y -5-[2-(4- 1 a chlorobenzylami-no )phenyl ]pyrazolo-3-carboxylicacid, mp 206".20 8. (dec,). From ethyl l -ethyl-6-(4-chlorobenzyl)pyrazolo[ l-,5-c]quinazolin 5(6H)-one-2- carboxylate.

4-Phenyl-5-[2-(4- chlorobenzylamino)phenyl]pyrazole-3-carboxylic acid,mp lO4lO6. From ethyl chlorobenzyl)-7-methylpyrazolo[ l ,5-c]quinazolin-(6H)-one-2-carboxylate.

Calculated for C H ClN o C, 68.40, H, 4.49; N, l().4() Found:

C, 68.]8; H, 4.30; N, l0.l9

5-[2-(4-Chlorobenzylamino)-3- methylphenyl]pyrazole-3-carboxylic acidhemihydrate, mp ll3ll6. From ethyl methylpyrazolo[ l ,5-c]quinazolin-5(6H )-one-2- carboxylate.

Calculated for C H ClN o l/2H O:

C, 6l.63; H, 4.74;'N, ll.98 Found:

C, 61.63; H, 4.43; N, ll.74.

5-[2-(4-Chlorobenzylamino)-5- methylphenyl]pyrazolo-3-carboxylic acid,mp l27l29. From methyl 6-(4-chlorobenzyl)-9- methylpyrazolo[ l,5-c]quinazolin-5(6H)-one-2- carboxylate.

Calculated for C ,,H .,ClN;,O.

' C, 63.25; H, 472; N, I229 Found:

C, 63.53; H, 4.96; N. l2.()4

5-[ 2-( 4-Chlorobenzylamino)-5- chlorophenyl]pyrazole-3-carboxylic acid,mp

287-289 (dec.). From ethyl 6-(4-chlorobenzyl)-9- chloropyrazolo[ l,5c]quinazolin-5(6H )-one-2- carboxylate.

Calculated for C H CI N O C, 56.37; H, 3.62; N, ll,6() Found:

C, 55.9]; H, 3.70; N, 10.77

5-[2-(4-Chlorobenzylamino)-3-methyl-6-chlorophenyll-pyrazole-3-carboxylic acid, mp 899 1 From ethyl 6-(4-chl0roben2yl )-7-methyll O- chloropyrazolo[ l ,5-c]quinazolin-5(6H)-one-2- carboxylate.

l-phenyl-6-( 4- Calculated for ClxHL'gClgNuOgl C, 57.46; H, 4.02; N,ll.l7 Found:

C, 57.25; H, 4.22; N. 10.89

5-[2-(4-Chlorobenzylamino)-4-chloro-5- methoxyphenyl]-pyrazole-3-carboxylic acid mp l37-l39 (dec.). From ethyl6-(4-chlorobenzyl)-8- chloro-9-methoxypyrazolo[ 1,5-c ]quinazolin-5( 6Hone-Z-carboxylate.

Calculated for C,,,H Cl N -,O

C, 55.12; H, 3.85-,'N, 10,71 Found:

C, 54.86; H, 3.70; N. 10.63.

What is claimed is:

1. A pyrazole-B-carboxylic acid of the formula,

R COOH R4, I I

wherein R is a monovalent group selected from the group consisting ofhydrogen, C -C alkyl, phenyl, and monosubstituted phenyl in which thesubstituent is C C alkyl, C -C alkoxy, fluoro, chloro, or bromo; R is amonovalent group selected from the group consisting of methyl, phenyl,benzyl, and monosubstituted phenyl and benzyl in which the substituentis methyl, trifluoromethyl, methoxy, fluoro, chloro, bromo, ormethylsulfonyl; and R and R are monovalent groups independently selectedfrom the group consisting of hydrogen, methyl, methoxy, fluoro, chloro,and bromo, with the limitation that R;, and R, must be different unlesseach of R and R is hydrogen.

2. The compound of claim 1, which compound is 5- (2-anilinophenyl)pyrazole-3-carboxylic acid.

3. The compound of claim 1, which compound is 5- [2-( 3trifluoromethylanilino )phenyl ]pyrazole-3- carboxylic acid.

4. The compound of claim 1, which compound is 5-[2-(4-chlorobenzylamino)phenyl]pyrazole-3-

1. A PYRAZOLE-3-CARBOXYLIC ACID OF THE FORMULA,
 2. The compound of claim1, which compound is 5-(2-anilinophenyl)pyrazole-3-carboxylic acid. 3.The compound of claim 1, which compound is5-(2-(3-trifluoromethylanilino)phenyl)pyrazole-3-carboxylic acid.
 4. Thecompound of claim 1, which compound is5-(2-(4-chlorobenzylamino)phenyl)pyrazole-3-carboxylic acid.